The maintenance of production systems is important in order to ensure production efficiency and safety. In connection with complex production systems, such as nuclear power plants, scheduled maintenance and repair procedures, usually implemented in connection with a computerized maintenance management system (CMMS), are often voluminous and unwieldy. In addition, procedures for responding to failures within a complex plant prepared in anticipation of certain failures (e.g., equipment degradation), are often performed without an appreciation of the impact of the failure on the stated safety, operating or cost performance goals of the plant. As a result, the preventive and corrective maintenance procedures associated with complex plants using conventional computerized maintenance management methods have been inefficient and/or ineffective.
The traditional approach to performing maintenance and responding to failures in complex plants or systems has been to apply maintenance and repair procedures without an appreciation of the context in which the maintenance or repair will occur. For example, a typical system may address a failure of a valve (e.g. a leak) by calling for replacement of that valve. However, there is usually little or no concern for the context in which the component (here a valve) operates. For instance, a valve may perform an important safety function or may control the flow of a dangerous substance, and may therefore be critical to the safe operation of the plant. Alternatively, it may be part of the water supply system used to wash the plant floors, and therefore a leak in the valve is trivial. However, because systems have not generally considered the context in which systems and components in a plant function, the limited maintenance and repair resources of a plant may quickly become overwhelmed by long lists of tasks, many of which may be relatively unimportant to the safe or efficient operation of the plant.
Another aspect of maintaining complex systems is tracking the changes that inevitably occur to the system over time, and making appropriate adjustments to maintenance and repair procedures affected by those changes. For example, a component in a plant may be replaced by a component that performs an identical function, but that has a very different design requiring different maintenance procedures. Conventional systems have typically not accommodated or required notes or the creation of historical records for justifying and documenting such changes. Therefore, changed maintenance or repair procedures may not be reflected by the computerized maintenance management system, or unjustified changes may be questioned by maintenance personnel, resulting in inappropriate maintenance or repair.
In order to efficiently allow for a maintenance program to model a complex system, it is useful to provide ready-made component descriptions that can be included in the overall system model. Although such descriptions have been available, they have not addressed adjustments or modifications that are necessitated by the context in which the component functions within the plant. In general, the context of a component is related to the function that the component provides in relation to the system in which the component is included, where the system defines, at least in part, the stress, environment, risk and service demand placed on the component. As a result, the maintenance and repair procedures that are associated with the component descriptions fail to take into account the actual operating conditions and the ramifications of failure or particular failure modes of the associated components. This again can result in unnecessary or inappropriate maintenance and repair procedures for components in a plant. In addition, where modifications to models of plant components are necessary, conventional computerized maintenance management systems have been unable to efficiently identify symmetries in the subject plant in order to facilitate the appropriate reuse of customized models of plant components. Conventional management systems have also been of limited assistance in determining what spares should be stocked, and what spares do not need to be stocked, in order to facilitate the uninterrupted operation of a plant, without maintaining an unreasonable inventory of spares.